Lead is a metal found naturally in the environment and in manufactured products. Historically, major sources of lead emissions have been motor vehicles and industrial sources. As a result of the phasing out of leaded gasoline and the introduction of other state and national regulations, airborne lead concentrations decreased in the United States by 94 percent between 1980 and 2007. Industrial processes are now the major source of airborne lead emissions; these sources include utilities, lead smelters, waste incinerators and manufacturers of lead-acid batteries.

Health Effects

While lead emissions have fallen nationwide, scientific evidence about the impact of lead on health has increased dramatically since the EPA first issued a lead standard in 1978. Lead emitted into the air in the form of particles may be small enough to stay suspended in the air. People can inhale emitted lead directly, and they can ingest it after it settles onto surfaces or soils. Once in the body, lead is rapidly absorbed into the bloodstream, and it accumulates in bones. Lead exposure is associated with several health effects that have an adverse impact on kidneys, the cardiovascular system, central nervous system and and immune system. Children are more susceptible to the damaging effects of airborne lead than adults because they breathe in more air per minute, typically spend more time outdoors, and exhibit greater hand-to-mouth activity than adults. Children are also more vulnerable to the health effects of lead because their minds and bodies are developing rapidly.

Missouri’s Lead Legacy

Missouri’s long history of lead mining and processing began with French explorers in the early 1700s. Missouri continues to be a world leader in lead mining and processing. Historical lead mining areas include the old lead belt around Park Hills in St. Francois County and the tri-state lead area around Joplin in Jasper and Newton counties. Lead continues to be mined from the new lead belt, or Viburnum trend, in Iron and Reynolds counties. The Viburnum trend is the largest lead mining district in the world.  Herculaneum, located in Jefferson County, was the site of the nation’s last primary lead smelter prior to the site ceasing primary lead smelting operations in early 2014. Glover and Buick, both located in Iron County, also had primary lead smelting operations at one time. The smelter in Glover is no longer operating and the Buick facility is now used for secondary smelting, where lead is recycled from lead-acid batteries, picture tubes, spent ammunition and other lead-bearing material.

2008 3-Month Rolling Lead Standard

On October 15, 2008, the EPA revised its standard for lead. The revision strengthened the 1978 standard tenfold, decreasing the standard for airborne lead from 1.5 to 0.15 micrograms per cubic meter. The significantly lower standard has the potential to affect more areas of the state, which will be determined using data from the Missouri Department of Natural Resource’s expanded monitoring network that became operational in January 2010. 

Boundary Designations

Date EPA Approval Document

Submitted: December 2009


Lead Designation and Boundary Recommendation. 1.74 MB
Technical Support Document. 3.86 MB

Received: June 2010


EPA 120-Day Letter (1st round)
Attachment to EPA 120-day Letter (1st round)

Received: June 2011


Due to new monitoring requirements under the 2008 Lead NAAQS, EPA had two rounds of designations when this NAAQS was revised. The boundary designations for the second round in Missouri did not change from the first round. The EPA letter for this second round of designations can be found below:
EPA 120-Day Letter (2nd round)

November 22, 2011  

Final Boundary Designations for the 2008 Lead NAAQS
Federal Register Notice


Date EPA Approval Document

MACC Adoption: December 2011

Federally Approved Plan: 79 FR 48994

State of Missouri Plan for Implementation, Maintenance and Enforcement of National Ambient Air Quality Standard



EPA Approval


MACC Adoption: March 2013

Federally Approved Plan: 79 FR 62572

Attainment Demonstration for the 2008 Lead National Ambient Air Quality Standard – Herculaneum Consent Judgement


EPA revised the Lead NAAQS in 2008, lowering the standard to 1/10th of the level of the standard that was established in 1978. In revising the standard, EPA also changed the form of the standard from an average over a three-month calendar quarter to a rolling three-month average.


EPA Approval


MACC Adoption: March 2013

Federally Approved Plan: 80 FR 52190l)

Attainment Demonstration for the 2008 Lead National Ambient Air Quality Standard – Buick

MACC Adoption: July 2013

Federally Approved Plan: 80 FR 52190

Modification to the Attainment Demonstration for the 2008 Lead National Ambient Air Quality Standard- Buick Consent Judgment Modification

Exide Technologies - Canon Hollow Facility


EPA Approval


MACC Adoption: September 2014


2008 Lead National Ambient Air Quality Standard Compliance Plan – Exide

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